Epilepsy and its related syndromes may be classified according to whether the associated seizures are partial or generalized, and whether the etiology is idiopathic or symptomatic/cryptogenic. Several important pediatric syndromes can be further grouped according to age of onset and prognosis. Epilepsy is one of the most common and disabling neurologic disorders in childhood. These may be divided into the epileptic encephalopathies of infancy and early childhood, febrile convulsions, and benign partial and generalized syndromes of later childhood and adolescence.
At present, the International League Against Epilepsy classification of epilepsy syndromes according to presumed localization (partial, generalized, undetermined) and etiology (idiopathic, cryptogenic, symptomatic). In clinical practice, it is often useful to conceptualize epilepsy syndromes according to their usual age at presentation, which greatly facilitates syndrome identification in new patients and recognizes the age-related expression of many childhood epilepsies. Definitional problems exist for many pediatric epilepsy syndromes, particularly the epileptic encephalopathies of early infancy, the benign epilepsies of infancy and childhood, the myoclonic epilepsies of infancy and early childhood, and the idiopathic generalized epilepsies of childhood and adolescence. (Epilepsia. 1996; 37 Suppl 1:S26-40).
TABLE 1Epilepsy syndromes according to usual age at onsetPeriodEpilepsy classificationNeonatal periodBenign neonatal convulsionsBenign neonatal familial convulsionsMiscellaneous neonatal seizuresInfancyFebrile seizuresEarly infantile epileptic encephalopathyEarly myoclonic encephalopathyInfantile spasmWest syndromesSevere myoclonic epilepsy of infancyBenign myoclonic epilepsy of infancyBenign partial epilepsy of infancyBenign infantile familial convulsionSymptomatic/cryptogenic partial epilepsiesEarly childhoodEpilepsy with myoclonic absences(toddler and preschoolLennox-Gastaut syndromeage)Epilepsy with myoclonic-astatic seizures(Doosesyndrome)Acquired epileptic aphasia(Landaw-Kleffner syndrome)Epilepsy with continuous spike-waveduring low-wave sleepEpilepsy with gastric seizures andhypothalamic hamartomaSymptomatic/cryptogenic partial epilepsiesChildhood (School age), Childhood absence epilepsyadolescence and youngadulthood
Some childhood-onset epilepsy syndromes are well defined and easily recognizable. These include benign rolandic, various syndromes with absence, the Landau-Kleffner syndrome (LKS), and continuous spike-wave inslow sleep. Others have somewhat vague characteristics including the Lennox-Gastaut syndrome. Some are still very difficult to define including benign occipital epilepsy and myoclonic-astatic epilepsy.
The term benign epilepsy is used to refer to a group of pediatric epileptic disorders in which remission and lack of significant neurologic sequalae are expected in the vast majority of patients. These disorders are idiopathic, occur in otherwise healthy children, and have (with rare exceptions) a strong genetic component. They include generalized epilepsies and partial epilepsies. These epilepsies are presented according to the age of onset, starting from the neonatal period. Although the prognosis of neonatal convulsions remains poor, benign neonatal convulsions are differentiated by their generally good prognosis. Two syndromes in which no metabolic, hypoxic-ischemic, or structural etiology is apparent are benign familial neonatal convulsions and benign idiopathic neonatal convulsions. (Regarding the former syndrome, some authors prefer to identify it by the term familial neonatal convulsions, dispensing with the adjective benign.) These include generalized, as well as partial, epilepsies. The generalized epilepsies discussed are limited to childhood absence epilepsy, which is also called pyknolepsy, and juvenile absence epilepsy, also known as epilepsy with nonpyknoleptic absences or epilepsy with spanioleptic absences. The benign partial epilepsies include benign partial epilepsy of childhood with centrotemporal spikes, benign occipital epilepsy, and benign epilepsy with affective symptoms.
In addition, presentation of variability of features as well as recent genetic findings and correlations have led to an expansion of the syndrome to include Benign Myoclonic Epilepsy (BME), Severe Myoclonic Epilepsy of Infancy Borderland (SMEB), Severe Infantile Multifocal Epilepsy (SIMFE), and Intractable Childhood Epilepsy with Generalized Tonic Clonic Seizures (ICE-GTC), Dravet syndrome (Ds), also known as Severe Myoclonic Epilepsy of Infancy (SMEI), is a rare and catastrophic form of intractable epilepsy that begins in infancy. Initial seizures are most often prolonged events and in the second year of life other seizure types begin to emerge. Development remains on track initially, with plateaus and a progressive decline typically beginning in the second year of life. Individuals with Dravet syndrome face a higher incidence of SUDEP (sudden unexplained death in epilepsy) and have associated conditions, which also need to be properly treated and managed. SIMFE presents in infancy but the neuro-developmental regression occurs between ages 3 and 6 years instead of between ages 2 and 4 years in the Dravet syndrome.
Lennox-Gastaut Syndrome (LGS) also known as Lennox syndrome, is a difficult-to-treat form of childhood-onset epilepsy that most often appears between the second and sixth year of life, and is characterized by frequent seizures and different seizure types; it is often accompanied by developmental delay and psychological and behavioral problems. As a general rule, the age of seizure onset in LGS patients is between the ages of two and six; however, this does not exclude the possibility that seizures can begin before age two, or after age six. The syndrome shows clear parallels to West syndrome, enough to suggest a connection. West syndrome or West's Syndrome is an uncommon to rare epileptic disorder in infants. Other names for it are Generalized Flexion Epilepsy, Infantile Epileptic Encephalopathy, Infantile Myoclonic Encephalopathy, jackknife convulsions, Massive Myoclonia and Salaam spasms. The term infantile spasms can be used to describe the specific seizure manifestation in the syndrome, but is also used as a synonym for the syndrome itself. West syndrome in modern usage is the triad of infantile spasms, a pathognomonic EEG pattern (called hypsarrhythmia), and developmental regression. Compared with other forms of epilepsy, Pediatric epilepsy is difficult to treat. It is very important that the condition is diagnosed as early as possible and that treatment begins straight away. However, there is no guarantee that therapy will work even in this case. There is to clarify a need for improved medication.